This invention relates to a linear tape storage system for storing linear tapes represented by DLT (Digital Linear Tape) and LTO (Linear Tape Open) and, in particular, to a magnetic tape head actuator assembly for use in such a linear tape storage system.
A linear tape storage system of the type has been developed as a backup for a computer system. A variety of linear tape storage systems have heretofore been proposed. For example, U.S. Pat. No. 5,862,014 discloses a digital linear tape drive which is for use in driving a magnetic tape such as DLT (Digital Linear Tape).
A digital linear tape drive (hereinafter may simply be referred to as xe2x80x9cdriving devicexe2x80x9d, xe2x80x9ctape drivexe2x80x9d, or xe2x80x9cdrivexe2x80x9d) is adapted to receive a tape cartridge (hereinafter may simply be referred to as xe2x80x9ccartridgexe2x80x9d) having a single reel (supply reel). The digital linear tape drive contains a take-up reel which is installed in a manner such that once a tape cartridge is inserted into the tape drive, a magnetic tape will be fed out from the tape cartridge. Then, the magnetic tape will be wound around the take-up reel by way of a head guide assembly (HGA). Here, the head guide assembly serves to guide a magnetic tape (hereinafter may simply be referred to as xe2x80x9ctapexe2x80x9d) fed out from the tape cartridge. A magnetic head operates to perform data exchange between the magnetic head and the magnetic tape. In detail, the head guide assembly comprises an aluminum plate having a boomerang shape and also comprises six large guide rollers which comprise bearings.
The head guide assembly is also called a tape guide assembly, which is disclosed, for example, in U.S. Pat. No. 5,414,585. On the other hand, an example of guide rollers has been disclosed in Japanese Unexamined Patent Publication No. 2000-100025 (JP 2000-100025 A).
In general, a tape drive contains a generally rectangular housing which has a common base, as disclosed in U.S. Pat. No. 5,793,574. In detail, the common base mounts two spindle motors (reel motors). The first spindle motor has a spool (take-up reel) permanently installed on the base. This spool is dimensioned so as to receive a magnetic tape streaming at a relatively high speed. The second spindle motor (reel motor) is adapted to receive a detachable tape cartridge. Such a detachable tape cartridge can be inserted manually or automatically into the drive through a slot formed in the housing of the drive. Once the tape cartridge is inserted through the slot into the drive, the tape cartridge is engaged with the second spindle motor (reel motor). Prior to the rotation of the first and second spindle motors (reel motors), the tape cartridge will be connected with the permanently installed spool (take-up reel), by virtue of a mechanical buckling structure. A plurality of rollers (guide rollers) are positioned between the tape cartridge and the permanently installed spool and are rotated to guide the magnetic tape when it is moved back and forth at a relatively high speed between the tape cartridge and the permanently installed spool.
However, the digital linear tape drive having the above-described structure is required to have a tape pulling device which enables the take-up reel to pull the magnetic tape from the supply reel. Such a tape pulling device is disclosed, for example, in International Publication No. WO86/07471. According to this International Publication, take-up leader means (first tape leader) is connected with the take-up reel while supply tape leader means (second tape leader) is fixed with the tape on the supply reel. Further, the first tape leader has a tab on one end thereof while the second tape leader has a locking hole, thereby allowing the tab to be engaged into the locking hole.
Further, it is also necessary to have a structure which can connect a first tape leader to a second tape leader. Such connection structure is disclosed in International Publication No. WO86/07295.
Further, Japanese Unexamined Patent Publication No. 2000-100116 (JP 2000-100116 A) discloses a xe2x80x9cleader tape retaining structurexe2x80x9d which is capable of retaining an end portion of a leader tape to a tape end retainer of the tape cartridge, without having to provide a thin leaf member protruding outwardly from one side of the leader tape (a second tape leader).
Moreover, U.S. Pat. No. 5,857,634 discloses a locking system which is useful for preventing an undesired rotation of a take-up reel of a tape drive under a condition when a tape cartridge has not been inserted into the tape drive.
On the other hand, Japanese Unexamined Patent Publication No. 2000-149491 (JP 2000-141491 A) discloses an example of a tape cartridge suitable for being inserted into a digital linear tape drive.
In addition, U.S. Pat. No. 6,241,171 discloses a tape drive which does not require the use of a buckling structure or a take-up leader, but enables a tape leader to be pressed forward by a take-up reel so that it moves from a tape cartridge.
The above tape drive further has a magnetic tape head actuator assembly. Such a magnetic tape head actuator assembly is located on a tape path defined by a plurality of rollers and positioned between a take-up spool and a tape cartridge. During the operation of the tape drive, the magnetic tape streams back and forth between the take-up spool and the tape cartridge. While streaming along the tape path defined as mentioned above, the magnetic tape is allowed to get extremely close to the magnetic head actuator assembly. One example of such magnetic head actuator assembly is disclosed in the above-mentioned U.S. Pat. No. 5,793,574.
FIG. 1 is used to illustrate a conventional tape drive containing a conventional magnetic tape head actuator assembly. In fact, FIG. 1 is a plan view showing a conventional tape drive with its top cover taken away for clear illustration.
As shown in the drawing, a tape drive 10xe2x80x2 is adapted to receive a tape cartridge (not shown) and contains a take-up reel 11 in its internal space. In practice, such a take-up reel 11 can also be called a spool. Specifically, the tape drive 10xe2x80x2 comprises a housing (chassis) 12xe2x80x2 which has a generally parallelepiped shape and a common base 12xe2x80x2a. Two spindle motors (reel motors) 13xe2x80x2 and 14 are mounted on the common base 12xe2x80x2a. In particular, the first spindle motor 13xe2x80x2 has a spool (take-up reel) 11 permanently installed on the base. The spool 11 has a relatively large size so that it can receive one roll of magnetic tape (not shown) streaming at a relatively high speed. The second spindle motor (reel motor) 14 is provided to receive a detachable tape cartridge. Such a detachable tape cartridge can be inserted automatically or manually into the drive 10xe2x80x2 along a direction represented by an arrow A in the drawing, passing through a slot 12xe2x80x2b formed in the housing 12xe2x80x2 of the drive 10xe2x80x2.
Once the tape cartridge is inserted through the slot 12xe2x80x2b into the tape drive, the tape cartridge will be engaged with the second spindle motor 14. In this way, prior to the rotation of the first and second spindle motors (reel motors) 13xe2x80x2 and 14, the tape cartridge will be connected with the spool (take-up reel) 11 installed in position by virtue of a mechanical buckling structure. A plurality of rollers (guide rollers) 15 are provided between the tape cartridge and the permanently installed spool 11, so as to guide a magnetic tape when the magnetic tape moves back and forth at a high speed between the tape cartridge and the spool 11.
The housing (chassis) 12xe2x80x2 is formed by an aluminum die-cast which is of course non-magnetic material. Accordingly, in order to stop a magnetism leakage from a magnet (not shown) contained in the second spindle motor 14, the second spindle motor 14 is covered by a plate 16 formed by a ferric magnetic material.
In fact, the tape drive 10xe2x80x2 further contains a magnetic tape head actuator assembly (hereinafter, simply referred to as actuator assembly) 20xe2x80x2. Such magnetic tape head actuator assembly 20xe2x80x2 is disposed between the take-up spool 11 and the tape cartridge, along a tape path (not shown) defined by the plurality of rollers 15. In operation, the magnetic tape will stream back and forth between the winding spool 11 and the tape cartridge. Subsequently, while streaming along the predetermined tape path, the magnetic tape gets close to the magnetic tape head actuator assembly 20xe2x80x2.
Next, FIGS. 2 to 5 will be used to explain a conventional magnetic tape head actuator assembly 20xe2x80x2. In detail, FIG. 2 is a perspective view showing an outer appearance of a conventional magnetic tape head actuator assembly 20xe2x80x2. FIG. 3 is an exploded perspective view in which the magnetic tape head actuator assembly 20xe2x80x2 shown in FIG. 2 has been separated into a tape head assembly 30 and a head sending mechanism 40xe2x80x2. FIG. 4 is a perspective view partially showing the magnetic tape head actuator assembly 20xe2x80x2 shown in FIG. 2, as well as a bearing holder 50xe2x80x2. FIG. 5 is an enlarged plan view illustrating the magnetic tape head actuator assembly 20xe2x80x2 shown in FIG. 1.
As shown in FIG. 3, the magnetic tape head actuator assembly 20xe2x80x2 comprises the tape head assembly (hereinafter, simply referred to as head assembly) 30 and the head sending mechanism 40xe2x80x2. The tape head assembly 30 has a magnetic head (head) 31 arranged in the vertical direction, and a head holder 32 holding the magnetic head 31, as well as a pair of flexible print circuits (FPC) 33 which are provided for effecting an electric connection between the magnetic head 31 and an external circuit (not shown).
The head holder 32 comprises a head holding portion 321 for holding the magnetic head 31, a pair of mutually opposed flange portions 322 each protruding from an upper end of the head holding portion 321 and extending in a direction perpendicular to the head holding portion 321. Each flange portion 322 has a hole 322a for receiving a screw 34 which is allowed to engage with the flange portion 322 by virtue of the hole 322a. In this manner, the tape head assembly 30 and the head sending mechanism 40xe2x80x2 (which will be described in more detail later in the present specification) may be installed in position by means of the flange portions 322. Further, the head holding portion 321 has an opening 321a formed in substantially the center thereof. By way of the opening 321a, one end of each of the flexible print circuits (FPC) 33 is allowed to be electrically connected with the magnetic head 31.
On the other hand, the head sending mechanism 40xe2x80x2 comprises 1) a lead screw (which is in fact a shaft formed with a plurality of screw threads) 41xe2x80x2 having a rotational center axis O and a plurality of screw threads 41xe2x80x2a, 2) a head lift 42xe2x80x2 having a generally square-shaped opening 42xe2x80x2a, capable of holding and at the same time moving the tape head assembly 30, 3) a split nut (hereinafter, simply referred to as xe2x80x9cnutxe2x80x9d) 43xe2x80x2 located within the opening 42xe2x80x2a of the head lift 42xe2x80x2 so as to be fixed within the head lift 42xe2x80x2, said split nut having a plurality of screw grooves engageable with the screw threads 41xe2x80x2a of the lead screw 41xe2x80x2, 4) a lead screw gear 44xe2x80x2 attached to the lower end of the lead screw 41xe2x80x2 and capable of rotating the lead screw 41xe2x80x2 about the rotational center axis O by virtue of other driving means.
Here, the split nut 43xe2x80x2 is provided to move the head lift 42xe2x80x2 (upwardly or downwardly) in a direction along the rotational center axis O, corresponding to the rotation of the lead screw 41xe2x80x2 about the rotational center axis O.
Further, the split nut 43xe2x80x2 has a pair of splits (slits) 432xe2x80x2 (but only one is shown in the drawing) orientated in a direction parallel to the rotational center axis O and separated from each other by 180 degrees in the circumferential direction. Moreover, the split nut 43xe2x80x2 has a pair of projections 433xe2x80x2 each protruding outwardly from the upper end of the nut. The pair of projections 433xe2x80x2 are allowed to engage into nut holding grooves formed on a pair of side walls of the head lift 42xe2x80x2. In this way, the screw grooves of the split nut 43xe2x80x2 are engageable with the screw threads 41xe2x80x2a of the lead screw 41xe2x80x2, thereby making it possible to move the head lift 42xe2x80x2 upwardly or downwardly along the rotational center axis O of the lead screw 41xe2x80x2.
In addition, the split nut 43xe2x80x2 has an annular groove 434xe2x80x2 formed on the outer periphery surface of the nut. A doughnut-like spring (circular spring) 48 is engaged in the annular groove 434xe2x80x2. Here, the doughnut-like spring 48xe2x80x2 is a special coil spring formed into a doughnut-like configuration. With the use of such a doughnut-like spring 48xe2x80x2, an inward compressing force can be applied to the nut 43xe2x80x2. However, in order to alleviate an undesired deformation of the nut 43xe2x80x2, such a nut 43xe2x80x2 is also formed with an annular space 435xe2x80x2 orientated in a direction perpendicular to the rotational center axis O.
Accordingly, when the lead screw 41xe2x80x2 of the actuator assembly 20xe2x80x2 (the head sending mechanism 40xe2x80x2) is rotated in the clockwise direction or the counter clockwise direction, the head lift 42xe2x80x2 and the head assembly 30 attached on the head lift will be caused to move in the upward or downward direction along the rotational center axis O, corresponding to the rotation of the lead screw 41xe2x80x2.
However, a combination of the split nut 43xe2x80x2 with the doughnut-like spring 48xe2x80x2 can serve as a backlash preventing mechanism for preventing a backlash of the actuator assembly 20xe2x80x2. In more detail, for the purpose of preventing a backlash which will possibly occur when the head lift 42xe2x80x2 moves corresponding to the rotation of the lead screw 41xe2x80x2, the doughnut-like spring 48xe2x80x2 is used to cause an elastic deformation of the split nut 43xe2x80x2 having a split (slit) 432xe2x80x2, thereby inwardly pressing the lead screw 41xe2x80x2 by virtue of an inwardly facing radial force.
Further, as shown in FIG. 4, the actuator assembly 20xe2x80x2 (the head sending mechanism 40xe2x80x2) is kept vertical on the chassis 12xe2x80x2 by virtue of the bearing holder 50xe2x80x2. In practice, the bearing holder 50xe2x80x2 has a through hole 50xe2x80x2a formed in the central portion thereof, in a manner such that the pair of flexible print circuits (FPC) 33 may be inserted therethrough.
Namely, the pair of flexible print circuits (FPC) 33, as shown in FIG. 3 and FIG. 4, are extending from the magnetic head 31, passing through the opening 321a of the head holding portion 321, further passing through the slots formed between the pair of side walls on one hand and the split nut 43xe2x80x2 on the other (all located in the opening 42xe2x80x2a of the head lift 42xe2x80x2), and finally passing through the through hole 50xe2x80x2a formed in the bearing holder 50xe2x80x2.
As described in the above, when a conventional actuator assembly 20xe2x80x2 is attached to the tape drive 10xe2x80x2, the pair of flexible print circuits (FPC) 33 effecting an input to and an output from the magnetic head 31, are required to extend through the opening 42xe2x80x2a in which the central lead screw 41xe2x80x2 of the head lift 42xe2x80x2 as well as the split nut 43xe2x80x2 have already been disposed.
Further, with regard to the bearing holder 50xe2x80x2 capable of vertically holding the head sending mechanism 40xe2x80x2 on the chassis 12xe2x80x2, it is necessary for the pair of flexible print circuits (FPC) 33 to extend through the central through hole 50xe2x80x2a. As a result, there would occur a problem that it is difficult to attach the actuator assembly 20xe2x80x2 to the chassis 12xe2x80x2 and another problem that it is also difficult to detach the actuator assembly 20xe2x80x2 from the chassis 12xe2x80x2.
Moreover, there would occur a further problem that when the pair of flexible print circuits (FPC) 33 are caused to extend through the holes 42xe2x80x2a as well as the hole 50xe2x80x2a, the pair of flexible print circuits (FPC) 33 are likely to get damaged. In addition, a still further problem is that when a used magnetic head 31 (tape head assembly 30) is to be replaced by a new one, an increased amount of man-hours will be necessary to effect such a maintenance.
Accordingly, it is an object of this invention to provide an improved actuator assembly which can be easily attached to or detached from a chassis.
It is another object of this invention to provide an improved actuator assembly whose one pair of flexible print circuits (FPC) can be prevented from being damaged when the actuator assembly is attached to or detached from a chassis.
It is a further object of this invention to provide an improved actuator assembly which needs only a decreased amount of man-hours when its magnetic head (tape head assembly) is replaced by a new one.
According to this invention, there is provided an actuator assembly (20) capable of moving a head assembly (30) in a vertically extending axial direction by virtue of a head sending mechanism (40). The head assembly (30) comprises a magnetic head (31) extending in the vertical direction, a head holder (32) for holding the magnetic head (31) and having an opening (321a) formed in substantially the central position thereof, a pair of flexible print circuits (33) extending through the opening (321a) of the head holder (32) and effecting an electrical connection between the magnetic head and an external circuit. The head sending mechanism (40) comprises a lead screw (41) having a plurality of screw threads and having a rotational axis (O) extending in the axial direction thereof, a head lift (42) mounting the head assembly (30) and having a through hole allowing the lead screw (41) to extend therethrough. In particular, the actuator assembly (20) of the invention is characterized in that the head lift (42) comprises a cylindrical portion (421) having a hollow opening (42a) formed in the center thereof, while the pair of flexible print circuits (33) are arranged in a manner such that the cylindrical portion (421) is wound by the flexible print circuits (33).
Further, the actuator assembly (20) of this invention is preferred to be formed in a manner such that the head sending mechanism (40) has a head guide (47) which is attached to the head lift (42) and is formed with a plurality of screw grooves engageable with the lead screw (41), so that the head guide (47) can move the head lift (42) in the vertical direction along the rotational axis, corresponding to the rotation of the lead screw (41). A preferred embodiment of the head sending mechanism (40) also has a backlash preventing mechanism (43, 48) arranged in the hollow opening of the cylindrical portion of the head lift, thereby constantly pressing the head lift in one direction along the rotational center axis of the lead screw. In detail, the backlash preventing mechanism is preferred to be formed by a pre-pressing bush (43) and a compressing coil spring (48). The pre-pressing bush (43) is disposed within the hollow opening of the cylindrical portion of the head lift and has a plurality of screw grooves engageable with the lead screw. The compressing coil spring (48) is also disposed within the hollow opening of the cylindrical portion of the head lift, and interposed between the pre-pressing bush (43) and the head lift (42), thereby constantly providing a pressing force which presses the head lift in the axial direction of the lead screw.
Moreover, the actuator assembly (20) of this invention is also preferred to be kept vertical on a chassis (12) by virtue of a bearing holder (50), while the pair of flexible print circuits are preferred to extend out through one side of the bearing holder (50).
The above reference numerals in the brackets are used only for better understanding of this invention, together providing only one example which should not be utilized to limit the scope of this invention.